Long before any building codes were published, conventional roof framing methods developed through practice, resulting in approaches to roof framing that are as varied as the framers themselves. In the past, methods described by the three main building codes (BOCA, UBC, and SBC), though similar, differed based on climatic factors—such as expected wind and snow loads—local habits, and available materials. Between the Eastern and Western codes, there were even different names for identical parts. Combining these disparate styles and standards into a single code—the International Residential Code (IRC)—was no easy feat, and seemingly fundamental aspects of roof construction are still up for debate.
Understanding this history provides perspective on why the treatment of roof construction in the IRC and the associated Wood Frame Construction Manual (WFCM) allows for such broad interpretation. But when it's boiled down, there are essentially two standard methods of roof construction, each having some flexibility. They're most easily...
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